Artificial cervical and lumbar discs, disc plate insertion gun for performing sequential single plate intervertebral implantation enabling symmetric bi-disc plate alignment for interplate mobile core placement

ABSTRACT

An artificial replacement disc includes a pair of substantially parallel plates formed to occupy a space defined by vertebral endplates, each of the plates including a plurality of spikes on a first surface and a concave trough formed on a second surface opposite of the first surface. A mobile core includes a core rim with opposing convex surfaces extending from opposite sides of the core rim, the mobile core being capable of being disposed between the pair of plates to permit the vertebral endplates to move relative to one another. The spikes on each of the plates extend substantially away from the mobile core and the convex surfaces are formed to integrally fit within the concave trough of at least one of the plates. The core rim limits lateral movement of the mobile core relative to the parallel plates. One or more insertion tools for inserting and implanting the replacement disc are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application60/788,720 filed on Apr. 4, 2006, copending U.S. patent application Ser.No. 11/019,351, filed on Dec. 23, 2004 and Ser. No. 10/964,633, filed onOct. 15, 2004, U.S. Provisional Application Nos. 60/578,319 filed onJun. 10, 2004, 60/573,346 filed on May 24, 2004, 60/572,468 filed on May20, 2004, 60/570,837 filed on May 14, 2004, and 60/570,098 filed on May12, 2004, and U.S. patent application Ser. No. 11/487,415 filed on Jul.17, 2006, the entire contents of all of the above identified patentapplications are hereby incorporated by reference.

BACKGROUND

This description relates to a three piece mechanical total cervicalartificial disc, which includes two spiked cervical plates and a mobilecore. The disc may be inserted into the cervical intervertebral discspace using a novel disc plate insertion gun which performs sequentialsingle plate intervertebral implantation enabling symmetric bi-discplate alignment for inter plate mobile core placement. This cervicaldisc design and method of implantation avoid the cumbersome and arduousimplantation techniques of many other artificial cervical disc designsimproving safety, improving bone-plate insertion/integration, allowingmultiple-level disc placement, preserving vertebral body integrity,eliminating the need for excessive disc space distraction, anddecreasing procedure length. This description also relates to a modifiedapplication of the disc plate inserter design from copending, relatedapplications describing posterior placed total artificial disc (PTTLAD).The modified disc plate inserter allows posterior lumbar sequentialplacement of two opposing disc plates rather than simultaneous two discplate placement as outlined in our previous publication. The modifieddisc plate inserter enables implantation of the PTTLAD into narrowerlumbar disc spaces which were not accessible with our previous lumbardisc plate inserter.

Cervical and lumbar discs are entering the clinical neurosurgical andorthopedic markets. The benefits of these artificial discs are wellknown and have been thoroughly reviewed in our prior and co-pendingprosthetic disc patents, including Provisional Application 60/788,720filed on Apr. 4, 2006, copending U.S. patent application Ser. No.11/019,351, filed on Dec. 23, 2004 and Ser. No. 10/964,633, filed onOct. 15, 2004, U.S. Provisional Application Nos. 60/578,319 filed onJun. 10, 2004, 60/573,346 filed on May 24, 2004, 60/572,468 filed on May20, 2004, 60/570,837 filed on May 14, 2004, and 60/570,098 filed on May12, 2004, and U.S. patent application Ser. No. 11/487,415 filed on Jul.17, 2006, the entire contents of each of which are hereby incorporatedby reference. In one or more of the foregoing applications, we describedfour different cervical artificial disc embodiments which expanded intwo or three-dimensions. This description presents an evolutionarysimplification of these embodiments, e.g., with fewer small parts, whichexpand in only one dimension, and can be inserted very simply andefficiently. Accordingly, the advanced cervical disc design of thepresent application is a geometric modification of previous lumbar discdesigns in one or more of the above-referenced patents, e.g., U.S.Patent Publication No. 2007/0198089 A1.

The cervical disc design of the present application differs fromapproaches of the background art which typically describe two-piecedesigns, e.g., as opposed to the three disc designs of the presentapplication. In the two-piece designs, one piece consists of either anupper or lower cervical disc plate with a central trough to accommodatethe opposing disc plate. The other piece, the opposing disc plate, hasan incorporated dome shaped immobile core. The immobilized core isstationary and does not move. Semi-constrained artificial motion occursas a result of the troughed plate movement against and around theimmobilized core.

One or more of these designs are described in the following exemplarypatent documents, including U.S. Pat. No. 5,314,477, filed Mar. 4, 1991(Thierry Marnay), entitled “Prosthesis for intervertebral discs andinstruments for implanting it;” U.S. Pat. No. 6,113,637 (Gill et al.),filed Oct. 22, 1998, entitled “Artificial intervertebral jointpermitting translational and rotational motion; U.S. Pat. No. 6,540,785B1 (Gill et al.) filed on Mar. 24, 2000, entitled “Artificialintervertebral joint permitting translational and rotational motion;”U.S. Pat. No. 6,8899,735 B2 (Bradley J Coates et. al.) filed on Oct. 2,2002, entitled “Modular intervertebral prosthesis system,” U.S. Pat. No.6,908,484 B2 (Zubok et. al.) filed on Mar. 6, 2003, entitled “Cervicaldisc replacement.” In each of the foregoing two-piece designs of thebackground art, the artificial implant is implanted within the vertebralbodies either by using attached hinges, keels or some form of extensionwhich accommodates placement of vertebral screws.

The present inventors have determined that one disadvantage of most ofthese systems is that placement of the prosthesis is arduous, and timeconsuming, and can destroy a substantial part of the vertebral bodyafter insertion of the device. The designs that use screws have thepotential risks of screw pull out and secondarily esophageal injury,screw breakage, and/or inability to perform multilevel disc placement.Furthermore the fact that these designs do not have a mobile core leadsto substantially constrained motion.

Similarly, U.S. Patent Publication No. 2007/0173936 A1 (Hester) filed onJan. 23, 2006, describes a design which includes spikes, also includes atwo-piece design with an immobilized core. One or more embodiments ofthe present application includes a mobile core which more closelysimulates natural semi-constrained motion of a healthy cervical disc.U.S. Patent Publication No. 2005/0021146 A1 (de Villiers et al.) filedMay 26, 2004 consists of two separate plates placed which are insertedsimultaneously as one unit, after which a mobile core is inserted inbetween the plates. However, the plates include keels which can damagevertebral bodies, and prevent multilevel placement. U.S. Pat. No.6,001,130 (Bryan), filed Oct. 6, 1997, describes a one piece design.However, the one-piece design involves an arduous placement techniqueinvolving disc space distraction, and the use of hinges and screws,limiting multi-level placement.

SUMMARY

One or more of the embodiments of the present application overcome oneor more of the above-described shortcomings of the background art. Forexample, a cervical disc design and tool for implantation of thecervical disc is an improvement over one or more of the above mentioneddesigns of the background art. Specifically, the spikes allowintegration into the vertebral body, e.g., with relatively small spikes,without damaging the vertebral bodies. This is particularly important iffuture prosthetic or fusions need to be performed at that level. Thecervical plates are inserted sequentially with a novel cervical plateinsertion gun. The advantage of the cervical plate insertion gun is thatthe method of implantation is quick and efficient. No disc spacedistraction is needed and hence there is no fear of damaging ordisarticulating posterior cervical facets. It can also be placed intonarrower spaces without distraction. The mobile core of the presentapplication also more closely approximates the natural semi-constrainedmotion of a healthy disc more so than the above mentioned discs.

Additional advantages of our posterior placed total lumbar artificialdisc (PTTLAD) lumbar disc design have been fully reviewed in ourco-pending patents, each of which have been incorporated by referenceherein. The present lumbar disc plate inserter design offers twoadditional advantages over previous embodiments. First, the inserterdesign grasps the plates more securely. In addition, the sequentialplacement of the different plates allows placement of posteriorartificial discs into narrower disc spaces.

In one general aspect, an artificial spinal disc includes a pair ofsubstantially parallel plates formed to occupy a space defined byvertebral endplates. Each of the plates including a plurality of spikeson a first surface and a concave trough formed on a second surfaceopposite of the first surface. A mobile core includes a core rim withopposing convex surfaces extending from opposite sides of the core rim,the mobile core being capable of being disposed between the pair ofplates to permit the vertebral endplates to move relative to oneanother. The spikes on each of the plates extend substantially away fromthe mobile core and the convex surfaces are formed to integrally fitwithin the concave trough of at least one of the plates. The core rimlimits lateral movement of the mobile core relative to the parallelplates.

Implementations of this aspect may include one or more of the followingfeatures. For example, the plates and mobile core can be sized andshaped to integrally fit within a space defined by cervical vertebralendplates and/or lumbar vertebral endplates. Each trough can be disposedin a center of each respective, parallel plate. The troughs can beshaped to receive the convex surfaces of the mobile core and the corerim can be shaped to receive outer edges of the troughs with an integralfit. The substantially parallel plates can include a plurality ofconically shaped spikes.

The mobile core rim may include at least a first substantially ringshaped member having a raised edge and a second substantially ringshaped member having a raised edge. The first and second ring shapedmembers may each define respective cavities where the convex surfacesare respectively positioned within and extend from. The plates cancomprise an elliptical shape.

In another general aspect, an artificial disc insertion system includesan artificial disc having a pair of substantially parallel plates formedto occupy a space defined by vertebral endplates, each of the platesincluding a plurality of spikes on a first surface and a concave troughformed on a second surface opposite of the first surface. The discincludes a mobile core having a core rim with opposing convex surfacesextending from opposite sides of the core rim, the mobile core beingcapable of being disposed between the pair of plates to permit thevertebral endplates to move relative to one another. The spikes on eachof the plates extend substantially away from the mobile core and theconvex surfaces are formed to integrally fit within the concave troughof at least one of the plates. The core rim limits lateral movement ofthe mobile core relative to the parallel plates. The system alsoincludes a surgical tool.

The surgical tool for inserting the artificial disc between vertebralendplates, the tool includes a handle portion having a trigger, an upperdisc plate release button, and a lower disc plate release button. Thesurgical tool also includes an insertion portion extending distally awayfrom the handle portion, the insertion portion includes an upperreplacement plate releasing portion and a lower replacement platereleasing portion. The upper replacement plate releasing portionincludes a release handle and a release link configured to engage andrelease a periphery of an upper replacement plate, e.g., to releasablysecure the upper replacement plate therebetween. The lower replacementplate releasing portion includes a release handle and a release linkconfigured to engage and release a periphery of a lower replacementplate, e.g., to releasably secure the lower replacement platetherebetween.

Implementations of this aspect may include one or more of the followingfeatures. For example, the mobile core and plates can be sized andshaped for a cervical disc replacement. The mobile core and the platescan be sized and shaped for a lumbar disc replacement. The mobile corerim may include at least a first substantially ring shaped member havinga raised edge and a second substantially ring shaped member having araised edge. The first and second ring shaped members may each definerespective cavities where the convex surfaces are respectivelypositioned within and extend from. The plates can include an ellipticalshape.

In another general aspect, a surgical tool for inserting an artificialdisc between vertebral endplates includes a handle portion comprising atrigger, an upper disc plate release button, and a lower disc platerelease button. The tool also includes an insertion portion extendingdistally away from the handle portion, the insertion portion comprisingan upper replacement plate releasing portion and a lower replacementplate releasing portion. The upper replacement plate releasing portionincludes a release handle and a release link configured to engage andrelease a periphery of an upper replacement plate, e.g., to releasablysecure the upper replacement plate therebetween. The lower replacementplate releasing portion includes a release handle and a release linkconfigured to engage a periphery of a lower replacement plate, e.g., toreleasably secure the lower replacement plate therebetween.

Implementations of this aspect may include one or more of the followingfeatures. For example, the insertion portion may include an upper tipportion and a lower tip portion. The upper tip portion and the lower tipportion may be curved to facilitate posterior insertion of a lumbarreplacement disc in a patient. At least one of the upper or lowerreplacement plate releasing portions can include a leaf spring, atension cable and a wedge portion proximally disposed relative to therespective release handle and the release link. Each of the upper andlower replacement plate releasing portions can include a leaf spring, atension cable and a wedge portion proximally disposed relative to therespective release handle and the release link. The tool can include areplacement disc plate driver portion for driving a replacement discplate from a first, proximal position toward a second, distal position.The upper replacement plate releasing portion is configured to secure anupper replacement plate in a position opposite from and axially alignedwith a center of a lower replacement plate held within the lowerreplacement releasing portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an anterior (or posterior) view of an exemplary cervicalartificial disc.

FIG. 1B is an isometric view of the cervical artificial disc of FIG. 1A.

FIG. 1C is an exploded view of the cervical artificial disc of FIG. 1A.

FIG. 1D is a superior (or inferior) view of the cervical artificial discof FIG. 1A.

FIG. 2A is a side view of an exemplary cervical artificial disc mobilecore.

FIG. 2B is an isometric view of the exemplary cervical artificial discmobile core.

FIG. 2C is a front (or back) view of the exemplary cervical artificialdisc mobile core.

FIG. 3A is a side view of an exemplary cervical artificial disc superioror inferior plate.

FIG. 3B is a top oblique-trough side view of the exemplary cervicalartificial disc superior or inferior plate.

FIG. 3C is a top oblique-spike view of the exemplary cervical artificialdisc superior or inferior plate.

FIG. 3D is a front-trough side view of the exemplary cervical artificialdisc superior or inferior plate.

FIG. 3E is a front-spike side view of the exemplary cervical artificialdisc superior or inferior plate.

FIG. 4A is a cross-sectional view of a cervical disc core showing theangular movements about the x-axis of the cervical disc core withrespect to the upper and lower cervical plates (lateral bending).

FIG. 4Bi is a front view of later cervical disc bending.

FIG. 4Bii is a side view of flexion/extension cervical artificial discmotion.

FIG. 4Ci is a front view of the artificial disc showing the rotations ofthe mobile core between the two cervical disc plates about the x-axis(lateral bending or roll).

FIG. 4Cii is a side view of the artificial disc showing the y-axis(flexion/extension or pitch).

FIG. 4Ciii is a perspective view of the artificial disc showing thez-axis (rotation or yaw).

FIG. 5A is a front view of a cervical disc plate insertion gun.

FIG. 5B is a top view of the cervical disc plate insertion gun.

FIG. 5C is a bottom view of the cervical disc plate insertion gun.

FIG. 6A is a perspective, left-side, cut-away view of the cervical discplate insertion gun.

FIG. 6B is a left side, bottom angle view of the cervical disc plateinsertion gun.

FIG. 6C is a right side, top angle view of the cervical disc plateinsertion gun.

FIG. 6D is a right side, bottom angle view of the cervical disc plateinsertion gun.

FIG. 6E is a cut-away view of the tool tip lower cervical discreplacement plate release mechanism.

FIG. 7A is a view of an outside left enclosure of the cervical discplate insertion gun.

FIG. 7B is a view of an inside left enclosure of the cervical disc plateinsertion gun.

FIG. 7C is a view of an outside right enclosure of the cervical discplate insertion gun.

FIG. 7D is a view of an inside right enclosure of the cervical discplate insertion gun.

FIG. 8A is a top view of inner components of the cervical plateinsertion gun including the lower insertion handle.

FIG. 8B is a lower insertion handle bottom view.

FIG. 8C is top view of a lower insertion link.

FIG. 8D is bottom view of the lower insertion link.

FIG. 8E is a view of the wedge link.

FIG. 8F is a top view of the upper insertion handle.

FIG. 8G is a lower view of the upper insertion handle lower view.

FIG. 8H is a close-up bottom view of a rear portion of the upperinsertion handle.

FIG. 8I is a close-up, top view of a forward portion of the upperinsertion handle.

FIG. 8J is a top view from left of the upper insertion release link.

FIG. 8K is a top view from a right side of the upper insertion link.

FIG. 8L is a view of a manual upper disc replacement plate driver.

FIG. 8M is a view of a trigger spring.

FIG. 8N is a view of a trigger.

FIG. 8O is a view of a wedge.

FIG. 9A is a perspective cut away view of an exemplary lumbar disc plateinsertion gun.

FIG. 9B is a cut-away view of the tool tip of the lower lumbar discreplacement plate release mechanism.

DESCRIPTION OF PREFERRED EMBODIMENTS

The Medical Device of FIG. 1-9.

Referring now to FIGS. 1-9, the above described problems of thebackground art can be solved in the cervical spine (and lumbar spine)after the performance of an anterior complete cervical discectomy. Thedisc device 10 includes an upper cervical plate 100 and lower cervicalplate 110, one of which is inserted first by a plate insertion gun 500.The opposite (second) cervical disc plate 110 is then inserted with theplate insertion gun 500 maintaining parallel opposition, with oppositeplates 100, 110 and troughs 102, 112 perfectly aligned. A mobile core150 is then inserted and sandwiched in-between both cervical plates 100,110.

FIGS. 1A-D illustrate different views of the cervical artificial disc10. The disc 10 includes an upper plate 100 and a lower plate 110. Eachplate has a plurality of spikes 101, 111, e.g., six spikes 101, 111 oneach plate in a preferred embodiment, on an outer surface of therespective plate, and a centralized trough 102, 112 on an inner surfaceof each plate 100, 110.

FIGS. 2A-C illustrate different views of the cervical mobile core 150.The core 150 has a centralized base rim 151 with a superior convexity152 which interacts with the trough 102 of the upper plate 100, and aninferior convexity 153 which interacts with the trough 112 of the lowerplate 110.

FIGS. 3A-E illustrate different views of the cervical plate (superior orinferior) 100 (110). The plate 100 includes a base 114. On an uppersurface of the inferior plate 110 is a trough 112. On a lower surface ofthe inferior plate 110 are 6 peripherally arranged spikes 111. Theposition of the trough 112 and spikes 111 are reversed for the superiorplate (100). A groove 113 is defined by the trough 112 (102) and base114 (104) of each plate 110 (100).

FIG. 4A illustrates a cross-sectional view of the cervical artificialdisc 10 and the degrees of motion of the mobile core 150 movement aboutthe x-axis with respect to the upper plate 100 and lower plate 110. Eachdisc plate 100 can bend about the x axis by 4.39 degrees clockwise andcounter-clockwise (lateral bending). This means that a disc plate 100,110 can move − or +8.78 degrees with respect to the opposite plate 110,100.

FIG. 4B illustrates a front view of lateral bending of the artificialdisc 10 (FIG. 4Bi), and a side view illustrating flexion-extension ofthe cervical disc 10 about the y axis which is 4.39 degrees in eitherflexion or extension.

FIG. 4C illustrates the rotation of the mobile core 150 between twocervical plates 100, 110 about the x (FIG. 4Ci), y (FIG. 4Cii) and z(FIG. 4Ciii) axes. Rotation about the x-axis is referred to as roll(alpha) which is lateral bending. Rotation about the y axis is referredto as pitch (Beta) which is flexion/extension. Rotation about the z axisis referred to as yaw (gamma) which is axial rotation. These figuresdisplay different views that show a reference frame for the discassembly 10 with an origin O at the center of the core 150. The axes ofrotation pass through the spherical face of the core 150 which is lowerthan 0 but are parallel to both the x and y axes. The rotation of thedisc plates 100, 110 about the z-axis is constrained only by the spinemotions once the disc 10 is implanted.

FIGS. 5-8 illustrate the components of the cervical disc plate insertiongun 500. Various opening mechanism functions will be described ingreater detail hereinafter with respect to FIGS. 5-8. The handle 512 ofthe opening mechanism is made up of left and right enclosures 501, 502(FIGS. 5, 6, and 7). FIG. 7 illustrates the inside and outside aspectsof left and right enclosures 501, 502. These enclosures 501, 502 areheld together by five enclosure fastening screws 590 (FIG. 6B). Thehandle 512 holds the mechanism used to insert the upper disc plate 100and lower disc plate 110 (FIGS. 5-6, and FIG. 8) into the vertebrae. Themechanism has two functions, including: 1) Holding onto the disc plates100, 110 until the user releases them, and 2) opening the tip 560 andforcing one disc plate at a time into a vertebra.

1. Holding Onto the Discs Until User Releases Them

The mechanism has two tips 565, 580 each holding a disc plate 100, 110.The lower tip 580 is composed of two parts: the lower insertion releaselink 576 and the lower insertion release handle 551 (FIGS. 6 and 8). Theupper tip 565 includes two parts: the upper insertion handle 550 and theupper insertion link 575 (FIGS. 6 and 8). Each tip 565, 580 works like a“lobster claw” that holds a disc plate by the “groove” 552 on itscylindrical extrusion. When the tip 565, 580 is closed the two opposingparts e.g. the lower insertion release link 576 and the lower insertionrelease handle 551 (FIGS. 6 and 8) hold a disc plate 110 firmly.

A tip 580 opens to release a disc plate as follows. A lower tensioncable 571 pulls on the lower insertion release link 576 (FIGS. 6 and 8)that pivots about the lower release pin 598 (FIG. 6) and opens up a gapbig enough to loosen the grip on the disc groove 552. The lower tensioncable 571 (FIG. 6) can only exert a tensile force to open the lobsterclaw 580. The natural state of the lobster claw 580 is to be closed.This is ensured by pre-loading the lower insertion release link 576 withthe help of a leaf spring 599 cut into the lower insertion releasehandle 551 (FIGS. 6E and 8). The lower tension cable 571 pulls on thelower insertion release link 576 (FIGS. 6 and 8) each time the userpresses on the lower release button 540. The lower tension cable 571 isclamped on one end by a lower rear crimp 592 (FIGS. 6 and 8). Hence whenthe lower release button 540 is pressed, the tension on the lowertension cable 571 increases (in the same way the tension of a guitarstring increase when one presses on the string with a finger). Thetension then pulls the lower insertion release link 576 forcing it toswing open. When the user lets go of the button 540, the tensiondisappears and the spring 599 carved in the lower insertion releasehandle 551 forces the lower insertion release link 576 to swing closed(FIG. 6E).

The upper tip 565 works in a similar fashion except that its opening istriggered by the upper release button 530.

2. Opening its Tip and Forcing One Disc at a Time into a Vertebra

The mechanism tips 565, 580 open each time the user presses on trigger510. When the trigger 510 rotates, it pushes on the wedge link 513 whichin turn pushes on the wedge part 525 (FIG. 8). The wedge part 525 iswedged at its front action end that creates a gap in between the lowertool tip 580 and upper tool tip 565 forcing them to open.

A typical disc insertion operation starts with a lower disc plate 110placed in the lower tip 580 and the opposing upper disc plate 100 placedon the upper side but away from the tip 565 (as shown in FIGS. 5, 6, and8). A channel 553 along the upper tip 565 that is formed by the upperinsertion release handle 550 and the upper insertion release link 575which holds the second disc plate 100 in place and serves to guide it tothe tip 565 when needed.

Once the tool tip 560 is inserted into the inter-vertebral space, thefirst disc plate 100 is inserted into the lower vertebra by opening thetool tip 560. To keep alignment, the lower tool tip 585, “lower lobsterclaw”, is kept closed (FIG. 6), securing the disc plate just inserted.The tool 500 should be left in place. The second, upper, disc 100initially placed in the upper tool half, away from the “upper lobsterclaw” 565 but away from the tip is then slid down to the end of theupper lobster claw 565 by a flexible and manually activated upper discreplacement plate driver 520 (FIGS. 6 and 8). Once the second disc 100is positioned at the tip of the upper “lobster claw” 565 (FIG. 6), thetool tip 560 is opened once more, i.e., the upper tip 565 and lowerlobster claw tip 580 are separated from each other, by virtue of thewedge 525 that is activated by the trigger 510, via wedge link 513action. Once the second, upper, disc plate 100 is inserted, the user canpress on the upper release button 530 and lower release button 540 torelease both discs (by opening the upper and lower “lobster claws” 565,580) and at the same time close the tool tip 560 (by releasing thetrigger 510). The tool tip 560 then closes while both “lobster claws”565, 580 remain open, leaving both disc plates 100, 110 in place. Thetool tip 560 can then be removed from the patient and a mobile coreplaced in between the two aligned disc plates 100, 110.

This anterior cervical disc gun can be modified and enlarged forplacement of anterior lumbar disc plates. FIG. 9A illustrates themodified posterior lumbar disc plate insertion gun 700. The gun 700 isidentical to the cervical disc plate insertion gun 500 except its tips660 are angled to allow insertion of the specifically sized lumbar discplates 100, 110 in the posterior lumbar spine underneath the thecal sac.

FIG. 9B illustrates an enlarged cut-away view of the tool tip 660 of thelumbar lower disc replacement plate release mechanism 670. The mechanism670 is identical to that described for the cervical mechanism which isillustrated FIG. 6E. The tips 660 of the lumbar tool are however,specifically designed and adapted for the typically bean shaped lumbardisc plates.

The Surgical Method

The method of insertion of the cervical artificial disc (or lumbarartificial disc) into the anterior cervical spine can be performed openmicroscopically, or closed tubularly, using endoscopic and/orfluoroscopic guidance.

After the adequate induction of anesthesia the patient is positioned inthe supine position. Routine exposure of the anterior cervical spine isperformed and the appropriate disc space is radiographically identifiedand exposed. A routine complete anterior cervical discectomy isperformed.

The cervical disc plates are inserted onto the cervical disc plateinsertion gun 500. The tips 560 of the gun 500 are placed into theintervertebral space. Fluoroscopy is used to assure centrality of discplate placement.

The trigger 510 of the gun 500 is depressed and the bottom plate 110 isinserted into the lower vertebrae. Once this penetrates the bone, thelower plate releasing button 540 is depressed, thereby releasing theplate from the inserter claws 580 (FIG. 6E). The second upper plate 100is now manually driven into the space by the gun's manual plate driver520. Because of the design of the gun 500, the upper plate 100 isperfectly aligned with the lower plate 110. The gun trigger 510 isdepressed and this drives the upper plate 100 into the upper vertebrae.The upper plate releasing button 530 is now depressed, releasing theupper plate 100 from the inserter lobster claws 565. The gun 500 isremoved from the interspace. A mobile core 150 of the appropriate heightis selected and placed in between the upper and lower cervical discplates 100, 110, respectively. The patient is closed routinely.

The surgical method for the posterior insertion of the PPLTAD into theposterior lumbar interspace can be performed open microscopically, orclosed tubularly, using endoscopic and or fluoroscopic guidance.

After the adequate induction of anesthesia the patient is positioned inthe prone position. A midline incision is made, the appropriateunilateral lamina is radiographically identified and exposed, and aunilateral hemi-laminotomy is performed preserving facet stability. Acomplete discectomy is performed, and the superior and inferiorendplates are exposed. The lumbar plate insertion gun 700 is placedunderneath the thecal sac. Fluoroscopic guidance may be used to verifycentrality of lumbar disc plate placement. The trigger of the gun 700 isdepressed which leads to insertion of the lower lumbar disc plate 100into the lower vertebra. The lower lumbar disc plate releasing button isdepressed which releases the plate from the inserter claws 551 (FIG.9B). The second upper plate 100 is now manually driven into theinterspace by the gun's 700 manual plate driver (520). Because of thedesign of the gun mechanism as described above, the second plate 100 isnow perfectly aligned with the first lumbar disc plate 110. The guntrigger is depressed, and this drives the upper plate 100 into the uppervertebrae. The upper lumbar disc plate release button is now depressedand this releases the upper lumbar disc plate from the claws of theinserter gun 700. The gun 700 is removed from the space. Anappropriately sized mobile core 150 is now inserted in between upper andlower lumbar disc plates 100, 110. The patient is closed routinely.

The current device allows safe placement of lumbar and cervicalartificial discs into the spine without intervertebral distraction, andtherefore places minimal tension on facet joints. The method ofinsertion is quick, gentle, and time efficient. The plate insertion guncould potentially be adapted for other inter joint orthopedic devices,and further adaptations may have applications in manufacturing, toy,carpentry and other industries.

What is claimed is:
 1. An artificial disc insertion system comprising:an artificial disc comprising: a pair of substantially parallel platesformed to occupy a space defined by vertebral endplates, each of saidplates including a plurality of spikes on a first surface and a concavetrough formed on a second surface opposite of the first surface; and amobile core having a core rim with opposing convex surfaces extendingfrom opposite sides of the core rim, the mobile core being capable ofbeing disposed between the pair of plates to permit the vertebralendplates to move relative to one another, wherein the spikes on each ofsaid plates extend substantially away from the mobile core and saidconvex surfaces are formed to integrally fit within the concave troughof at least one of the plates, wherein the core rim limits lateralmovement of the mobile core relative to the parallel plates; and asurgical tool for inserting the artificial disc between vertebralendplates, the tool comprising: a handle portion comprising a trigger,an upper disc plate release button, and a lower disc plate releasebutton; and an insertion portion extending distally away from the handleportion, the insertion portion comprising an upper replacement platereleasing portion and a lower replacement plate releasing portion, theupper replacement plate releasing portion comprising a release handleand a release link configured to engage and release a periphery of anupper replacement plate; and the lower replacement plate releasingportion comprising a release handle and a release link configured toengage and release a periphery of a lower replacement plate.
 2. Thesystem according to claim 1, wherein the mobile core and plates aresized and shaped for a cervical disc replacement.
 3. The systemaccording to claim 1, wherein the mobile core and the plates are sizedand shaped for a lumbar disc replacement.
 4. The system according toclaim 1, wherein the mobile core rim includes at least a firstsubstantially ring shaped member having a raised edge and a secondsubstantially ring shaped member having a raised edge.
 5. The systemaccording to claim 4, wherein the first and second ring shaped memberseach define respective cavities where the convex surfaces arerespectively positioned within and extend from.
 6. The system accordingto claim 5, wherein the plates comprise an elliptical shape.
 7. Asurgical tool for inserting the artificial disc between vertebralendplates, the tool comprising: a handle portion comprising a trigger,an upper disc plate release button, and a lower disc plate releasebutton; and an insertion portion extending distally away from the handleportion, the insertion portion comprising an upper replacement platereleasing portion and a lower replacement plate releasing portion, theupper replacement plate releasing portion comprising a release handleand a release link configured to engage and release a periphery of anupper replacement plate; and the lower replacement plate releasingportion comprising a release handle and a release link configured toengage and release a periphery of a lower replacement plate.
 8. Thesurgical tool according to claim 7, wherein the insertion portionincludes an upper tip portion and a lower tip portion.
 9. The surgicaltool according to claim 8, wherein the upper tip portion and the lowertip portion are curved to facilitate posterior insertion of a lumbarreplacement disc in a patient.
 10. The surgical tool according to claim7, wherein at least one of the upper or lower replacement platereleasing portions comprises a leaf spring, a tension cable and a wedgeportion proximally disposed relative to the respective release handleand the release link.
 11. The surgical tool according to claim 10,wherein the upper and lower replacement plate releasing portions eachinclude a leaf spring, a tension cable and a wedge portion proximallydisposed relative to the respective release handle and the release link.12. The surgical tool according to claim 7, further comprising areplacement disc plate driver portion for driving a replacement discplate from a first, proximal position toward a second, distal position.13. The surgical tool according to claim 7, wherein the upperreplacement plate releasing portion is configured to secure an upperreplacement plate in a position opposite from and axially aligned with acenter of a lower replacement plate held within the lower replacementreleasing portion.
 14. A surgical tool for inserting an artificial discbetween vertebral endplates, the tool comprising: a handle portioncomprising a trigger, and at least one of an upper disc plate releasebutton and a lower disc plate release button; an insertion portionextending distally away from the handle portion, the insertion portioncomprising at least one of an upper replacement plate releasing portionand a lower replacement plate releasing portion; the at least one of theupper replacement plate releasing portion and the lower replacementplate releasing portion comprising: a release handle and a release linkconfigured to engage and release a periphery of an upper replacementplate or a lower replacement plate, respectively.
 15. The surgical toolof claim 14, wherein the insertion portion includes an upper tip portionand a lower tip portion.
 16. The surgical tool of claim 15, wherein theupper tip portion and the lower tip portion are curved to facilitateposterior insertion of a lumbar replacement disc in a patient.
 17. Thesurgical tool of claim 14, wherein the at least one of the upperreplacement plate releasing portion and the lower replacement platereleasing portion comprises a leaf spring, a tension cable and a wedgeportion proximally disposed relative to the respective release handleand the release link.
 18. The surgical tool of claim 14, furthercomprising a replacement disc plate driver portion for driving areplacement disc plate from a first, proximal position toward a second,distal position.
 19. The surgical tool of claim 14, wherein the upperreplacement plate releasing portion is configured to secure an upperreplacement plate in a position opposite from and axially aligned with acenter of a lower replacement plate held within the lower replacementreleasing portion.